Replace express with builtin node server

Alternative to long-standing webpack-contrib#212

Express in this project does not add much value. Middleware api is not
necessary for 1.5 middlwares. We can try to use node server directly.

Serving static is left for express middleware. Can be replaced with
something smaller in another PR.

package.json

@@ -37,11 +37,11 @@
     "acorn-walk": "^8.0.0",
     "chalk": "^4.1.0",
     "commander": "^6.2.0",
-    "express": "^4.17.1",
     "filesize": "^6.1.0",
     "gzip-size": "^6.0.0",
     "lodash": "^4.17.20",
     "opener": "^1.5.2",
+    "serve-static": "^1.14.1",
     "ws": "^7.3.1"
   },
   "devDependencies": {

src/viewer.js

@@ -4,7 +4,7 @@ const http = require('http');
 
 const WebSocket = require('ws');
 const _ = require('lodash');
-const express = require('express');
+const ejs = require('ejs');
 const {bold} = require('chalk');
 
 const Logger = require('./Logger');
@@ -13,6 +13,7 @@ const {open} = require('./utils');
 const {renderViewer} = require('./template');
 
 const projectRoot = path.resolve(__dirname, '..');
+const viewsRoot = path.join(projectRoot, 'views');
 
 function resolveTitle(reportTitle) {
   if (typeof reportTitle === 'function') {
@@ -48,23 +49,33 @@ async function startServer(bundleStats, opts) {
 
   if (!chartData) return;
 
-  const app = express();
-  app.use(express.static(`${projectRoot}/public`));
-
-  app.get('/', (req, res) => {
-    res.writeHead(200, {'Content-Type': 'text/html'});
-    const html = renderViewer({
-      mode: 'server',
-      title: resolveTitle(reportTitle),
-      chartData,
-      defaultSizes,
-      enableWebSocket: true
-    });
-    return res.end(html);
+  const serveStaticMiddleware = serveStatic(`${projectRoot}/public`);
+
+  const server = http.createServer((req, res) => {
+    if (req.method === 'GET' && req.url === '/') {
+      const html = renderViewer({
+        mode: 'server',
+        title: resolveTitle(reportTitle),
+        chartData,
+        defaultSizes,
+        enableWebSocket: true
+      });
+      res.writeHead(200, {'Content-Type': 'text/html'});
+      res.end(html);
+    } else {
+      serveStaticMiddleware(req, res, err => {
+        if (err) {
+          console.error(err.stack || err.toString());
+          res.writeHead(500);
+          res.end();
+        } else {
+          res.writeHead(404);
+          res.end();
+        }
+      });
+    }
   });
 
-  const server = http.createServer(app);
-
   await new Promise(resolve => {
     server.listen(port, host, () => {
       resolve();